Functional evaluation of motor insulation systems

AT PRESENT, all insulating materials are classified by chemical composition into groups with specified maximum operating temperatures. Because many materials, especially those in the organic group, differ widely in their stability toward heat aging, these definitions have become too restrictive. To replace this system, a new method of classification is proposed based on the ability of a material to perform an insulation function. This method is intended to apply specifically to random wound induction motors in the approximate range of 1 to 40 horsepower or to equipment using a similar insulation system.